Various devices, known generally as antennas, are advantageously employ to couple an electronic device to a time varying electromagnetic field. In diverse applications, antennas are used to couple power into and out of an electromagnetic field and to transmit and receive signalingly modulated electromagnetic fields. Circular spiral antennas have been used in a number of such applications. They are desirable for, among other characteristics, the production of circularly polarized electromagnetic radiation. A circularly polarized receiving antenna will receive a portion of an incoming signal regardless of the spatial orientation of the receiving antenna. Consequently, circular polarization is used extensively in communications applications where an orientation of a transmitting or receiving antenna may be altered in a way that is unpredictable or otherwise undesirable. For example, systems for communicating with orbiting and extra-orbital spacecraft typically employ circular polarization.
A square spiral antenna is a known variant of a circular spiral antenna. Square spiral antennas have certain advantages over circular spiral antennas. These advantages are particularly evident with respect to relatively low frequencies of electromagnetic radiation.
Notwithstanding their long use and well understood theory, circular and square spiral antennas exhibit deficiencies for which no satisfactory remedy has previously been presented. The corresponding long-felt, but unsatisfied need for improved devices is at last addressed in the substance of the present disclosure. Indeed, the present invention emerges from new insights and understanding of these deficiencies developed by the present inventors and reflected in the novelty of the corresponding inventions.